Apparatus for recording sounds



July 11, 1933. O DUNMNG 1,917,830

APPARATUS FOR RECORDING SOUNDS Filed July 10, 1950 2 Sheets-Sheet 1 FIG. 3a

FIG. 3b

H6. l a,

I INVENTOR M M. M RI BY flC awmkm ATTORN EY July 11, 1933. O DUNNING 1,917,830

APPARATUS FOR RECORDING SOUNDS Filed July 10, 1930 2 Sheets-Sheet 2 INVENTOR a, M. M24

A TORNEY Patented July 11, 1933 UNITED STATES PATENT OFFICE.

ORVILLE M. DUNNING, 0F ORANGE, NEW JERSEY, ASSIGHOR T0 THOMAS A. EDISON, INCORPORATED, OF WEST ORANGE, NEW'J'EBSEY, A CORPORATION OF NEW JERSEY nrrn'mrus FOB nnoonnme: scum Application aim July 10, 1930. Serial Ira-186,901.

This invention relates to apparatus; for recording sounds, and is particularly applicable to electrical and mechanical phonographs and the like. It is an object of this invention to provide apparatus capable of producing records of high quality, with high eficiency, and withoutthe usual necessity for precise adjustments and fine control of recording conditions. I

It is a further object of this invention to provide apparatus of the class described which will afford increased freedom in design of the recorder to the end-that highest efiiciency may be had under any particular expected operating condition.

it is a further object of this invention to provide apparatus by meanspf which the weight of the recorder may be increased as desired without resulting in increased pressure of the stylus on the record. i

It is a further object ofthis invention to provide apparatus of the class described by means of which the pressure exerted by the-stylus upon the record may be set to any desired value regardless of the weight of the recorder unit.

It is a further object of this inventionto provide apparatus of the class described which is so arranged that the apparatus may be operated under the optimum conditions by anyone, which does not require complicated adjustments, and which is sim ple, rugged, and reliable in operation.

The features of novelty which'li believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its fundamental principles and as to its particular embodiments will best be understood by reference to the specification and appended drawings, in which, Fig. 1 showsone form of electrical recording apparatus according to my invention as applied to a cylinder record. 1

Fig. 1a is a bottom plan view of the recorder unit comprising a part of the apparatus shown in Fig. 1.

Fig. 2 shows a modified form.

Figs. 3a and 3b are diagrams explaining principles of the form of apparatus illustrated in Fig. 2.

the principles of my invention.

In the various figures the same reference characters designate the same elements.

Fundamentally my invention contemplates the arrangement of the recorder. unit in such a manner that the pressure ofithe stylus on the record'ismainta'ined atany desired value regardless of the, weightr'ofvthe unit itself. This result .is achieved byisupporting the recorder attwo points on the record insuch a mannerlthatthe su porting force exerted hy the record is distributed between the two pomts of support in. anydesired proportion. One of thesepoints of support is the stylus which engages the record and the other is a non-vibratile bearing termed an advance ball which travels over the surface of the record and carries a part of the weight of the unit.

. placed some distance apart but they are so placed relatively to the remainder of the unit structure that a vertical line passing through the center of gravity of the unit, or its apparent center of gravity'.(which will be explained later) falls between the advance ball and the stylus. i

More particularly, the location of the center of gravity and the relative position of the advance hall and stylus with reference thereto and to each other are so chosen that exactly the desired pressure is effective on the stylus and the rest of the pressure of the unit on the record is carried on the advance ball.

Referring now more particularly to Fig. 1, l designates generically a recorder unit, in this instance of the electrical type, operating in any suitable way to vibrate the arm 2 which carries the recording stylus 3.- In the form shown the arm 2 is arranged to vibrate about point as a center t ereby causing the stylus 3 to execute an up and down motion suitable for IlIlSCl'lblIlg a socalled hill and dale record. The arm 2 1s an angular extension of an armature 2' which comprises part of the electrical means for imparting to the stylus 3 vibrations to be recorded.

The unit 1 may be carried laterally over the record by means of a bracket 5 pivoted to the unit at point 6. The bracket 5 may be suitably movably supported from a member 7 shown diagrammatically which may be actuated by the feed screw mechanism (not shown) to advance the unit along the record.

In the embodiment herein shown the link 5 does not exert any upward force upon the unit, but merely controls its position transversely of the record.

' The advance ball 4 is mounted upon the frame of the unit 1 and likewise contacts with the record 10. The advance ball is usually made from a jewel such as a sapphire, diamond, or the like, and consists of a short cylinder, one end of which is ground and polished to approximately a segment of a s here. This is usually of sufliciently large ra ius to prevent the weight carried upon it from mar ing appreciably the surface of the record which passes across it during the recording. The recording stylus 3 may be the usual form of jewel well known in the art. The advance ball 4 is preferably slightly oil'- set from the recorder stylus, as shown in Fig. 1a, so that the advance ball contacts with an uncut portion of the record. In Fig. 1a the arrow indicates the direction of move- 40 ment of the unit across the record during normal recording operation.

The center of gravity of the unit is considered to be located at point C on the center line of the unit. It will be noted that if a line AR be drawn from the tip of the advance ball to the tip of the recorder stylus a vertical line passing through the center of gravity C of the unit intersects the line AR at point X. a designates the angle between the hori- 5o zontal and the line AR. d designates the distance on this line to the point X. m is the distance from the advance ball to the center of gravity projected upon line AR and (1 represents the distance from the ad- 'vance ball to the recorder stylus.

The various vertical forces acting upon the unit in this case are the following:

(1) the force W actin vertically downward through the center of gravity and equal to the weight of the unit.

(2) the force W acting vertically upon the advance ball 4 and (3) the force W acting vertically upward upon the recorder stylus.

In order to analyze the conditions which upward obtain the unit may be considered as a stiff beam in a state of equilibrium. Under these conditions, taking moments about the point A W(d cos a) =W (d cos 11) dividing by From this it will be seen that the proportion of the weight or force at the point R'of engagement of the recorder stylus 3 with the record to the total weight of the unit is the same as the proportion of distance al to d.

From this equation it will be seen that the weight effective on the recorder stylus, that is the pressure exerted by the stylus on the record may be made to have any desired value. This weight or pressure may be decreased from any given value in a number of different ways.

First, the weight of the unit may be reduced, second, the angle a may be increased, third, the distance d may be increased, for example by moving the advance ball to the left or the recorder stylus to the right, or both, and fourth, the center of gravity may be shifted to the left so that al is decreased.

The first method, that is reducing the weight of the unit, requires no description. The second method, increasing the angle 0:, may be applied by moving the unit in a counter clockwisedirection on the record 10 by appropriately increasing the length of the link 5. The third method requires no explanation. The fourth method is indicated in Fig. 2 and explained with reference to Figs. 3a and 3b.

In Fig. 2 the unit 1 instead of being supported entirely against gravity by its contact with the record has an upward force applied to it by link 5 at the pivot 6. The link 5 in this instance may be extended beyond the pivot on support 7 and the counter Weight 11 may be attached, or a spring may be secured to the link which tends to rotate it clockwise. In any event of course the upward force exerted by the link 5 will be less than the weight of the unit since otherwise the unit would not remain upon the record.

This upward force exerted by the link 5 has the effect of shifting the center of gravity of the unit to the left in substantially the same way as the center of gravity would be shifted if an additional weight were attached at the left side of the unit, the center of gravity being displaced from its true position C to a new position C vA vertical line drawn through C intersects the line AR at a point nearer the advance ball than the point of intersection of line AR and a vertical line through C- and thus the ratio which represents the portion of the weight of the unit effective upon the recording stylus, is decreased. This condition may be considered mathematically by reference to Fig. 3a. Let R now represent the point of contact of the advance ball and record, and R the point of contact of the st Ins and record, W the wei ht of the unit, the force exerted upward y by the link 5, R the force exerted upwardly by the record on the stylus and R the force exerted upwardly by the record on the advance ball. The force X and the distance y will be brought into this discussion later and until they are further mentioned, they may be considered to be absent from the beam structure as shown. This simple beam may be considered equivalent to the recorder shown in Figure 2, W representing the weight of the unit applied at its true center of gravity, F the upward 'pull due to the counterbalance, and R and R the upward force exerted by the record on the advance hall and recorder stylus respectively. We will now obtain a general expression for B,

, and R in terms of W and F and the various horizontal distances between their lines of action represented by a, b and l.

llhen taking moments about R W.a=F.b +13 1, (1) trom which Then Now it will be understood that the forces F and W may be considered to be removed from the system and replaced by a single force which will give the same reaction. Let new force be called X and considered to be located at ahorizontal distance 3 from point it, as shown in Fig. 3a.. Then again taking moments about R X .y=R .Z (4) Substituting for R from (2) above X,.y=W.a-F.b (5) 5 Taking moments about R 1( 1- Substituting for R; from (3 1 .1) 0- m (5) and (7) form two simultaneous equations which may be solved for )& and 3 so that from R We ma We have now found an imaginary force X, which acts at a horizontal distance 3; call this force K the apparent weight 0 the unit; and the point at which it acts, a horizontal distance 3; from R the apparent center of gravity. As far as the forces applied by the record, R and R are concerned, this apparent weight applied at this apparent center of gravity will be exactly the same as the two forces, F and W. We can therefore refer to Fig. 3b in which I have substituted the letter W for X and apply to it the same analysis as hereinbefore given in connection with the structure shown in Fig. 1.

Thus it will be seen that the relation between all of the forces involved is known and the designer can predetermine the various forces and their locations in order to obtain any desired actual weight or pressure upon the stylus regardless of the weight of the unit. The same effect may be obtained as shown in Figs. 4 and. 5 in the first case by shaping the unit in such a manner that its center of gravity is displaced toward the advance ball as shown in Fig. 4 or by the attachment of a weight 14 at the side of the unit. In both of these cases I have shown the system as applied to a disc record instead of a cylindrical record.

It is clear that while I have shown my invention as particularly arranged for hill and also be applied with dale records, it may records as will be unso-called lateral cut derstood.

In all of the arrangements heretofore described the unit has been diagrammatically indicated as an electrical unit of any suitable type, eitherdynamic or magnetic, both of which are well known in the art, but it will be understood that the same principles may be applied in the case of a mechanical unit as shown in Figs. 6 and 7 wherein l2 represents the casing of any suitable form of mechanical sound box known in the art and having a diaphragm 13. The recording stylus is secured to the diaphragm in a known manner and the advance ball 4. is secured to the casing. The sound box may be carried upon a bracket 5 pivoted to the casing at point 6 as in the case of the electrical units, and as in-the cases already explained, the

' distribution'of. forces may be predetermined and controlled in the manner already exdisplacing the center of gravity to the left as already explained with reference to Fig. 2.

While I have shOWn and described certain preferred embodiments of my invention it will be understood that I do not desire to be limited to the precise arrangements shown and described since it will be apparent to those skilled in the art that the principles of m invention may be applied in various ways w1thin the scope of the appended claims. It is to be noted that the expression center of gravity used in the claims isintended to include both the true center of gravity and apparent center of gravity as herein explained.

It is to be understood that the construction and arrangement of any of the various forms of recorder units shown, may be such that the center of gravity of the unit will be spaced from the plane in which the record engaging points of the stylus and advance ball and the geometrical center of the unit are located. In such a case, while the line of action of the force under which the unit is biased to a position in which the stylus and advance ball engage the record (which line of action is a vertical line passing through the center of gravity of the unit) will not, of course, lie in said plane, a projection of said line of action upon a plane parallel to said line and passing through the record engaging points or ends of the stylus and advance ball will intersect the line connecting said ends at a point between the latter, and

the advance ball and stylus may be correctly described as being located on opposite sides of said line of action or of a vertical line passing through the center of gravity of the unit.

I claim:

1. 'A sound recorder unit comprising, in combination, a frame, a stylus vibratably carried by said frame for contact with a record, means associated with said stylus for imparting thereto vibrations to be recorded, and an advance ball mounted upon said frame for contact with said record, said advance ball and said stylus being located on opposite sides of a vertical line passing through the center of gravity of said unit.

2. A sound recorder unit comprising, in combination, a frame, a stylus vibratably carried by said frame for contact with a record, means associated with said stylus for imparting thereto vibrations to be recorded, and an advance ball mounted on said frame for contact with said record, said advance ball and said recording stylus being located on opposite sides of a vertical line passing through the center of gravity of said unit, and said unit being disposed on said record in such a manner that a line joining the record engaging points of said advance ball and stylus is at an angle to the horizontal.

3. A sound recorder unit comprising in portion of said record.

4. A sound recorder unit comprising in combination, a frame, a stylus vibratably carried by said frame for contact with a record, means associated with said stylus for imparting thereto vibrations to be recorded, an advance ball mounted upon said frame for contact with said record and means on which said frame is movably mounted, said frame being biased in respect of said mountim means to a position in which said stylus and advance ball both engage said record, said stylus and ball being located on opposite sides of the line of action of the force biasing the frame to said position.

5. A sound recorder unit comprising, in combination, a frame, a stylus vibratably carried by said frame for contact with a record, means associated with said stylus for imparting thereto vibrations to be recorded, and advance ball mounted upon said frame for contact with said record and means on which said frame is movably mounted, said frame being biased in respect of said mount- 1ng means to a position in which said stylus and advance ball both engage said record, said stylus and ball being located on opposite sides of the line of action of the force biasing the frame to said position and at such distances from said line of action that the stylus engages said record with a pressure less than the weight of the unit.

6. A sound recorder unit comprising, in combination, a frame, a stylus vibratably carried by said frame for contact with a record, means associated with said stylus for imparting thereto vibrations to be recorded, an advance ball mounted upon said frame for contact with the record, and means on which said frame is movably mounted, said frame being gravity-biased in respect of said mounting means to a position in which said stylus and advance ball both engage said record, said stylus and advance ball being located on opposite sides of a vertical line passing through the center of gravity of said unit.

This specification signed this 9th day of July, 1930.

ORVILLE M. DUNNIN G. 

